Alcohol and breast cancer risk: a case-control study from northern Italy

From May 1982 to June 1985 a hospital-based case-control study of diet and breast cancer (214 cases and 215 controls) was conducted in Milan in northern Italy, an area where wine consumption is widespread. The study used a detailed diet questionnaire to obtain an estimation of total calories as well as major micro- and macro-nutrient intake. The data thus allowed an investigation of the role of alcohol in breast cancer risk, adjusting for other dietary factors, in particular total energy intake. We found positive associations between breast cancer risk and total caloric intake (chi 2 trend = 6.05, P = 0.014) but no effect for the other nutrients, when adjusted for total caloric intake. The relative risk of breast cancer, for women reporting more than 24.35 g/day of alcohol consumption (highest quintile), was 2.1 (95% confidence interval (CI): 1.1-3.9) when adjusted for non-dietary risk factors for breast cancer and 1.8 (95% CI: 1.0-3.3) when adjusted for non-alcohol caloric intake. The relative risks were moderately elevated (50% or less) for low levels of consumption and comparable to those recorded in most American studies. This finding provides further support for a moderate association between alcohol consumption and breast cancer risk, even when allowance is made for potentially relevant nutrients.